Field of the Invention
The present invention relates to an electrode manufacturing method and apparatus for manufacturing an electrode by applying electrode ink to an electrode substrate.
Description of the Related Art
In general, an electrode manufacturing apparatus manufactures an electrode to be used in a fuel cell by applying electrode ink to an electrode substrate, such as carbon paper, while conveying the substrate. The electrode, if the coating thickness of the electrode ink is not appropriate, affects battery performances. It is therefore required to measure the coating thickness of the electrode ink to perform non-defective product determination.
A radiation measuring apparatus discussed in Japanese Patent Application Laid-Open No. 2011-196755 includes a radiation source and a sensor, and detects the coating thickness of an electrode substrate based on the intensity of radiation reaching the sensor from the radiation source through the electrode substrate.
The radiation measuring apparatus discussed in Japanese Patent Application Laid-Open No. 2011-196755 detects the thickness of the electrode substrate at both a coated portion and a non-coated portion to calculate the coating thickness based on a difference of the detected thicknesses. However, the apparatus does not detect the thickness of the coating portion and a non-coating portion at the same position. Therefore, when there is variation in the thickness of the electrode substrate, it is not able to accurately calculating the coating thickness.
Further, what is called a roll-to-roll manufacturing method may be employed in the electrode manufacturing. According to this manufacturing method, an elongated electrode substrate is conveyed from an unwinding roll to a winding roll while the electrode substrate is tensioned. Therefore, there are cases where the electrode substrate is stretched during the conveyance. Once such a stretching occurs, it is difficult to detect the thickness at the same position, and it is thus no longer possible to accurately calculate the coating thickness, as mentioned above.